I just had surgery and the surgeon and I thought it was to be one 5cm lipoma removed from my back. (photo)

I understand your concern and hope your are recovering from your surgery smoothly. It is not uncommon for lipomas to occur in clusters, some other times they appear as discrete lumps distributed all over the body. Lipomas are mostly slow benign deposition of fat cells wich are encapulated. When they grow in clusters they appear and one big lump. Histopathology is normally done to confirm the diagnosis and rule out liposarcoma. Liposarcoma is often deep seated and rapidly growing tumour, the size would often cause pressure symptoms and pain. 

Thank you for your question and for sharing your photograph.  It is not uncommon to have lipomas found in a cluster and the risk of malignancy is not greater in these cases.  Hope this helps.

I would say it is not that unusual to have a cluster of lipomas in one area, and this does not necessarily mean there is greater chance of a malignancy.  The large majority of lipomas are benign, as yours likely are.  Your surgeon will be able to know for sure after obtaining the pathology report.