Yep, sounds like suit squeeze... Doesn’t matter how much experience you have. These things can happen to anybody. Although we do try to avoid them.
I’ve been diving dry for quite a while, and still every now and then I’ll come up with one.
I think that sometimes the air in the suit becomes unevenly distributed and the pressure in an arm or a leg fails to equalize properly with the rest of the suit.
When I am diving with a tri-lam and a moderately heavy undergarment, I don’t feel them happening. However, lately I’m diving a 7mm neoprene suit and a very thin skin under it. With this suit, I’ feel the pinch.
The only thing that I can suggest is to "try" to be more attentative to drysuit inflation and air distribution within the suit.
If the above doesn’t work, then you’ll havee to come up with a really strange story to explain the marks. Something like "I was attacked by a mermaid" or a "lampray got me". Or something like that...