Intermittent back pain on workout. MRI showed hematopoietic matter. Is it common?

Hi. I had an MRI of my back because I was feeling intermittent back pain whenever I worked out and pulled a muscle in my lower back. The doctor just wanted to be sure that it was not a disc issue and just weak lower back and core muscles. The results showed no disc issue but on one line it said diffusely low signal within marrow of lumbar which may be within normal limits and represent hematopoietic matter but the possibility of an infiltration process could not be excluded. I am completely assymptomatic and have hadno history of cancers. I a going for a blood panel today but my friend who is a radiologist said that there is a very low likelihood anything to worry about I am a 43 year old male in perfect health. Do you agree that many people can have this result and it be benign?