Dad had tubular adenoma polyp removed at age 40. Heridatry? Symptoms of this?

Premalignant. Tubular adenomas can give rise to cancer if left in place, and having had one is a marker that he may get more. This does tend to run in the family. You'd do well to get occasional colonoscopies as health maintenance for yoruself. He should also continue to be checked.
Watch bowel habits. A tubular adenoma is benign and not likely hereditary. Make sure there were no "adenomatous" polyps which are pre-malignant and can be associated with hereditary syndromes. How did they find this in him- was he bleeding? 40 is young for routine colonoscopy, enless there wee symptoms, findings por family history. Please provide more detailed history.