just perplexed as to TEVA's awareness that they would receive a letter for the FDA by the end of January and is the FDA simply providing TEVA with this info out of courtesy or is it a common practice?
In most cases, FDA communicates regularly with sponsor company during regulatory review process especially when FDA has questions. So it is not surprising TEVA knew ahead of time a letter was coming. Companies usually don't comment on communication between FDA and sponsor companies until they receive official communication/letter. In this case, it was surprising TEVA disclosed it would receive a letter ahead of time, but it was not surprising TEVA knew ahead of time a letter was coming.
For example, GILD disclosed it received RTF today for its NDA filing. I am 99.9% certain GILD knew RTF well before it received official RTF letter. FDA would ask GILD to clarify the information indeed was not in NDA filing before formally issuing RTF.