Can your ideal frame size change with your riding experience?

[beetle]

Thanks for all the replies. I guess I should look at a new stem then.

It's very possible that you've become more flexible as you've ridden more. To address that, however, I would start with your current bike. I'd note that you should not use saddle setback to lengthen your reach. Your saddle position is largely a function of proper knee position over your pedals. Instead, you will probably want to start with a longer stem but be sure to increase your stem in small increments. You might also be able to handle a bit more saddle to bars drop. I'd start with the stem first though.

Indysteel: What sort of a increase do you think would be reasonable to start with?

I think I may have the LBS look at my saddle/pedal set up as well and see that I make sure that is right before changing anything else.

[RoadRaven]

I know you asked Indy, but I'll just chime in here....

Small increments in our house mean only 5mm/10mm at a time - thats 1/2 to 1 centimetre... about 1/2 and inch max.

If you are adjusting your stem (where the handlebars are) you should have/should be able to get spacers to slip on or to take off.

Personal example; I want to get lower and more aero on my TT bike, so we take one spacer out, then I ride for a couple of moths, then we remove another, and then I get my body used to that. I am ready to get lower again and will remove the last spacer after this Thursday's ITT. If I wat to get lower than that, I will need to flip the stem around...

There is an ideal height for your saddle based on how bent/straight your leg is. You'll need help for that.
If you choose to turn your seat post around so the angle changes (not all seat posts can do this) then you will need to mess around with height again. However, unless you lengthen or shorten your legs, you shouldn't need to play around with the seat height too much.