I would say that you need an adjustment. Also be aware that you will lose the HD signals much sooner than you would lose the SD signals due to the narrow KA beam.
You might just need to switch to the SD version of the program you are watching when you get a moderate to heavy rain.
Before you do anything, however, go into the receiver setup. Menu, setup, satellite, repeat satellite setup>hit the dash>signal strength. It will show the numbers for the 101 satellite which should all be very close to 100. On the right click on the + button beside where it shows 101 and you will see each of the other satellites numbers (ignore the (s) transponders you only care about c, ca and cb). Your only other satellites of concern are 99 and 103 and these should be in the 80's or above.
If they are much lower than what I mention then you need a service call or a ladder and a wrench as you likely just need to "tweak" the dish a hair left or right or up or down the smallest amount to bring in a better signal.