Finished tactics unit 33 (module 1)

Finished a module in one run for a change. Results were kind of lousy though... The unit was a mix of 1 move 2 move mate problems and 4 move mate problems. I guess it's because i've been doing 4 move mate problems for quite some time now and being focussed on them, because i was having a hard time solving the 1 move 2 move mate problems all of a sudden, while they are suposed to be easier. I do have to say i let my performance be dictated mainly by the minute (per problem) i was given to solve them. I was given a minute and a half for the 4 move mate problems, but they were much easier to solve within the given time span. Does this switching reaction sound familiar to anyone of my readers? Ofcourse it could've been that i just had a bad hair day ;-)