From what I have read, this is normal. If down the road, you get swelling in the salivary glands, that is also normal. The RAI can cause blockage, so when eating the glands swell. Massage helps along with warm compress.
I had RAI done almost 15yrs ago due to graves/hyper/goiter. Ended up with TT.
Just last year I actually had to have surgery to remove my right salivary glad due to swelling when I ate (painful) and lack of responding to antiboitics. When they went in to remove it they found my salivary gland chronically infected (sialenditis-sp?), a mass on the gland, two swollen lymph nodes- ALL came back good, no cancer.
I think it had to do witht the RAI, but who knows, I just know it was painful.