Blood in Urine (Lung Adenocarcinoma & Anal Canal Cancer, 2+ years in remission)

Hello!

First I would like to thank this board for a lot of information and encouragement. It has been extremely helpful. I would like to ask for an information about my mother. 

Short background:

My mother was diagnosed with anal canal cancer (Stage II) in May 2015, during the preparation for the radio/chemo therapy she was also diagnosed with early stage lung adenocarcinoma (Stage IB). Since the two tumors have different cell types they were viewed as two independent cancers. So she did a thoracoscopic surgery for her lung adenocarcinoma, then did two chemos for both cancers (cisplatin + paclitaxel), an additional two chemos for lung (carboplatin + paclitaxel), and radiotherapy (I think it is 30 Gy in total if I remember it correctly) for her anal canal cancer. She has been in remission after all the treatment (2+ years).

Starting from about two months ago, on her last follow-up exam, her urinalysis shows blood in urine. Specially RBC is 2 or 3 times of the normal high end. (Sorry my mother is living in another country so the unit is not the same, the actual number is 32.90 * 10^6 / L). She didn't find blood in urine in a previous follow-up exam about one year ago. She did have a kidney stone of 0.5 mm size but it has been there for a long time (at least the last 5 years). 

After the first urinalysis with blood in urine, she did a ultrasound exam as well as MRI scan (in her followup exam for anal canal cancer) and showed everything was normal.

Her doctor says it's better for her to continue monitor the situation by doing urinalysis once every month. 

I wonder if people have seen similar situations like this before? Is it a concern that something more serious may be behind (in terms of lung adenocarcinoma and anal canal cancer)?

Thank you for reading and help!