Yes...
I remember when I used to glide from RAE Farnborough, over the diamonds (the concrete area around some of the hangers) I was almost thrown out of the cockpit of the K-8.
My hour was up so I pushed the nose down to lose height, probably was doing 65 Knots (that was fast for her), the thermal was so tight that I punched through it in a fraction of a second. Hence the rapid ascent followd by a rapid descend and my arse leaving the seat.
I guess either one wing hit a thermal or the other the sink from a thermal and hence your roll.