TSH above normal, T4 high end of normal, why?

Had papillary carcinoma/follicular variant at age 25. Partial gland removal, then RAI ablation. I'm now 60. Levothyroxine dosage has been adjusted a few times but has mostly been .137 - .150. Recently had a blood draw and TSH was 6.55 (normal is .55-4.5) and Thyroxine (T4) Free, direct was 1.72 (normal is .82-1.77) - high end of normal. I asked PCP (via his MA) if increasing levothyroxine might be indicated due to high TSH and he wrote a script to increase from .137 to .150 with instructions to retest after 30 days. Haven't had the retest yet (next week likely) but wanted to inquire if high levels of both TSH and T4 are red flags to anyone? I don't think I've had this before (one has been high, the other low every previous test) so I'm wondering if I have pituitary malfunction. I haven't seen an endocrinologist since 2022 because, at that time he said clean thyroglobulin tests for 10+ years is considered cured. Side note: for at least the first 20 years post Dx, TSH suppression was protocol. Maybe 5 years ago my endo said that's no longer necessary when scans have been clean for as long as mine have. Any constructive comments are appreciated.