It could be bad if you are on flowering schedule. In that case you have to watch out for hermies. I would take my chance and continue growing, because even if I get hermies, I will probably still have some smokable harvest.
Some timers can't handle the currents that are going on while turning on/off a hid light. You have to change to a better quality timer.
Freaking timers drive me bat shit crazy. Lights suddenly go out when theyre not supposed to for some unknown reason. The digital timers are a pain in the ass to set. I have like 5 of them running off and on all the time and they drive me nuts.