MOM Asking for More Documents for my EP

Hi I have been in Singapore for almost 5 years. I have had 3 jobs here, first one for 8 months, second one for 2 years and 8 Months, and the third (my current) for 1 year 7 months. I am on a P1 currently, I am earning 8k p/m - but earn around 6-8k in bonus and commission payments per month. (last tax assessment showed I earnt 150k and the year before 167k - in basic and commissions)

I have recently been offered a new job, signed the papers, and they have applied for my EP - the new company is paying me 14k p/m and bonus comms will be quarterly (hence the higher basic)

I have 15 years of work experience 10 in the relevant field.

My application has been pending for a week, then my prospective new employers HR emailed me to say that MOM require additional documents namely;
1. contract of employment
2. Last Tax assessment
3. Company's existing business contracts with three of their largest clients...

Company submitted all the docs including my last 2 years of tax assessment - (the said the application is not rejected, but saying they need more documents to verify) - now i am just waiting... for a decision.

Should I be worried? Or is this something normal now? Few people in HR have told me that it is because of the fairly big jump in salary? - any advice would be much appreciated as I am keen to get started in my role!!!!

Thanks