Sorry I am asking too many questions today

Will highly appreciate if you help on this:
My Tier 2 visa expires next year however my employer is saying they need me to continue work for them so they are happy to sponsor me further. They said they are happy to pay me the Experienced rate.
The New Entrant rate for my SOC code is 25K and Experienced rate is 40K. My current salary is 28K.
So my question is: do they need to notify the UKBA if they increase my salary from 28K to 40K as this is a significant pay rise? Also, is there any problems with this or this is quite normal and legal? I was reading in Sponsors Guidance that they should not employ a Tier 2 General migrant if they are not planning to pay them the Experienced rate afterwards.
Will highly appreciate your help and sorry again for so many questions for today guys! Thanks a lot!