In the middle of an embroidery project, I had taken the hoop off to trim the fabric and the machine started making a ticking sound.  I looked at the screen and it had various color stripes on it which covered the entire screen.  I shut the machine off and turned it on again.  It seems to be okay and started where I had left off but I'm wondering if this is the start of a problem.  Any advice or ideas?  I'd rather not bother my dealer if it's just a one-time thing but if it's the start of an issue, I'd like to let him know.  He's over 2.5 hours away and we're in the middle of a snowstorm (6 inches added to what was already on the ground so I wouldn't be able to go for two months or so.
Ceil

A one-off event like this is super hard to diagnose. It sounds like an electronic rather than a mechanical issue. Given that this machine (15000) has a lot of software in it, there is a distinct possibility that the internal program has a bug that only happens when a precise set of circumstances occurs. Even without your distance and the weather, there's almost nothing your dealer can do without the problem being reproducible. Since it finished stitching from where you left off, that's a good sign. It probably happened in the screen display logic, rather than stitching logic. That would make it annoying, but not fatal. LCD screens require a pretty high voltage to light up, and there is a device called an inverter that generates the voltage for that. In certain circumstances it can make a ticking sound. The LCD display also has a bit of temperature sensitivity. Some have reported that it takes a few seconds for the screen to light up if the machine is cold and in a dark room. If you have a heater near the machine (and in your part of the country this time of the year I'd be sitting on a heater) it might have some effect.

In summary - if it's a one-off, no worries, life is good. If something is failing nothing can be done until it fails solidly enough to be discoverable by your dealer. The failing component could be the main circuit board, the LCD display board, or the power supply. It's unlikely your dealer would have those in stock, since they are all pricey and rarely fail. If it happens more than this once, call your dealer and ask him to call Janome technicians (specifically Gazmend if he is still there) and ask for an opinion. If they have seen it before, they can advise him as to what part is needed, he can order it, and you can make the trip when it will work for both you and him. (If you do have to make this call, a video from your phone could be invaluable.) Otherwise continue to use the machine without worry. It's almost certainly not something you did, and it may never happen again. Chalk it up to sun spots, cosmic rays, or the dodgy clam chowder you had for lunch.

Thanks, Jim.  I am a bit of a worrier but did manage to use it without a further problem for about another half an hour.  So, hopefully, it is just a glitch.  If it doesn't recur beforehand, I will mention it to my dealer when I make my yearly trek for a cleaning.  After I thought about it and noticed that I was very cautious not to hit the screen after that, I wondered it I hit it with my arm while putting the hoop back into position.  I usually don't use this machine during a storm and that it could also have been a short electrical glitch although I do have it on a newish serge protector.  There is no heater near the machine and the room is upstairs and usually around 58 degrees as we try not to use the electric heat upstairs instead relying on the pellet stove and furnace heat to rise from the first floor.  It's common here and makes for comfortable sleeping temperatures.  
Thank you very much for you help and advice.
Ceil