50d occasional mirror lag when shutter closed?

[NewbieInCS]

Been using my 50D for over 2years. 13000 photos. For the first time I am having "mirror lag" issue.

What happens is that for a fast shutter speed, say 1/320s, the mirror stays up for like 1/10-1/4s before it comes down. The exposure is perfect fine as metered for 1/320s, so I guess the shutter is closing, just the mirror is not dropping down. It happened like 3 or 4 times in 50 shots when my battery was low.

Having recharged the battery, I haven't had the problem again for the next 100 shots.

Is this a "glitch", low battery issue or something about to die?

 

[PilsnerLiam]

Camera trying to clear the buffer?

 

[adrianongs]

Camera trying to clear the buffer?

He was trying to say the the mirror flips up for a longer time than expected for 1/320 , so I guess it's not the buffer full ?

 

[Soundaholic]

I don't think it has anything to do with the buffer. All moving parts wear out over time, so maybe yours is just a rare occurrence that the mirror mechanism has been weakened over the years?