Define "after a while".  Tech inflation has been in the game since DL, and tends to cap around 170% (thereby 270% or 2.7x initial cost), but as the first ~25-50 techs don't impact tech inflation, most people never even notice it-by the time it happens, they're far enough along that it doesn't matter.

I have not looked into tech inflation as the TA "weapons" (also defenses and apparently also soldiering) cost ratio changes impact it, but the basic ideas behind it seem to be the same as it was in DL and in DA.

There have been reports of massive inflation, on the order of increasing by 400 or 500% in 10 turns or less, but that bug was squashed and anything you're noticing now similar to it is a glitch that is in all probability not reproduceable and would require a reinstall to fix.