The same thing happens with the Malekko 600. Though, like someone else mentioned, it has an expression control input to control the repeats. I think it's a common problem, I seem to remember other delays I've had doing that. It's really annoying and easy to forget about in the middle of a song - until you turn it back on. I wish it would just start back at "0" when turned back on and then ramp back into the craziness.
It's not exactly a 'problem', just something that is inherent to a self oscillating delay.