Hi Ann. The postdoc is actually is actually quite a few years older than I am. I have pinpointed the problem in that we work very differently. I like early mornings, and she prefers later starts. She is very outspoken while I am very quiet and like to get on with things (though not shy or introvert).
Early on, I realised these differences and we had a quick chat and offered to meet each other half-way (i.e, I would do my own thing but if I needed any help she would be there for me). It worked, for a while but it has gone back to normal again. By the way, the talk in Germany went well!