Update:Very interesting! I have the same thing, although it started to happen after I flashed kwbr X.XX some time ago and also I bought an unlimited data plan at the very same time. So I thought it was my cell provider who messed with these settings...
Previously, I always had "H" displayed no matter if there was any traffic activity or not.
After I flashed stock 3.14 WWE, I intentionally gave it a try and played with my device for several minutes, just to see what this ROM was about.
Interesting that the situation with 3G/H was exactly the same as on kwbr ROMs.
No data being transferred - you see 3G.
You open a web page - you see H while it's loading.