Family Visit Visa Application

[lapen123]

Hi Experts,
I need your help again!
I have applied for my parents family visit visa last week 02/07/2015 on priority service (I had to pay extra for that)...I received a call today from unknow number and lady caller said she was from Home Office and asked me if I have sponsored someone lately...I confirmed that I have sponsored my parents... she said she only had details for one applicant...then she asked for their names, DOB, what they do, my full name and address, my profession, who will pay for their travel and accomodation, Did I sponsor anyone else in last 2 year.
After I provided all the info. she said she will forward this info. to the Visa Clearance Officer and they will make a decision.

I have two questions:
1) my parents have visited us three times before but HO never called us...have they started calling lately?
2) I am bit worried why she had only one application details - my parents applied together as only one set of sponsored documents were there...would you know how the application are processed with one set of sponsored documents?
My dad ensured both applications plus sponsored documents are put in the same envelope by the agent at the application processing centre...
Thank you for your help in advance!