Just occurred to me -- my 630 started doing something similar a few weeks after I picked it up. I was able to exchange it at the dealer so don't know what the problem was in the end.

I'll dig through my notes and see if I had the same problem. Sorry I didn't think of this earlier...

M60ti, VP180, QS8, M2ti, EP500, PC-Plus 20-39
M5HP, M40ti, Sierra-1
LFR1100 active, ADA1500-4 and -8