I think it may have been showing in the iD editor as just a Cycle Path rather than Cycle & Foot Path, even though it had the necessary cycle/foot segregation tagging already.  It's just the iD editor being particular about things though - as rskedgell says, the original tagging had the same effect.

I've just seen a similar case while editing the segregated cycle path on the north side of the A13. There's no harm in 'upgrading' these tags like this so they look right when editing in iD.