Did your dog look like this? (Random image I found online)
Sounds like you're describing a play bow. It has nothing to do with suspicion, rather- it's a sign of "play mode" in a lot of dogs.
RATCHX3 High Jinks vom Neuanfang - Gotchya Day: 1/23/2013 DN, SG, SR, CA
Inspire Spark to Ignition! (Ignite) Gotchya Day: 10/8/2016
C-ATCH Pimg - RATO, UJJ (x2), DJX, HIT, CA, CGC, High in Games, Reserve High in Standard- CPE Nationals 2014