It was indeed, and I see your momentary braking (eventually). Good point.
No criticism of you, but if you had been indicating right, the bozo on the bike might have seen it and not cut you up. Personally, I think the Highway Code guidance on signalling on roundabouts is bad. Unless there is no other traffic to be affected, I always indicate on entering a roundabout - either left if I am taking the first exit, or right until I pass the last exit before mine, when I indicate left.
If there is a car on a roundabout not indicating, you don't know whether it is going straight on, or the driver is one of the many dozy clowns who do not bother to indicate. By the same token, you cannot assess from the lane positioning whether the driver is following the guidance, or the same sort of dozy clown who has no real clue about lane positioning, or simply took the least congested lane entering the roundabout in order to be held up as little as possible, and sod the Highway Code...
The way I do it, so long as I am indicating right other road users can be in no doubt about my intention NOT to leave the roundabout at the next exit, whatever lane I am in. I think that is safer.