Additional surgery recommended after lumpectomy

My mammogrpy in August showed a cluster of microcalcifications in the right breast.  I had a needle biopsy done last month and was diagnosed with DCIS.  My lumpectomy was done on October 16.  My surgeon is recommending a re-excision based on the lab findings as follows:
- Foci of residual ductal carcinoma of intermediate nuclear grade with foci of central calcification and necrosis, solid and cribriform pattern.
- ductal carcinoma in-situ, seven out of sixteen slides. largest focus measuring 0.4 cm.
- The ductal carcinoma in-situ present in close proximity, 0.1 cm from the anterior margin, 0.3 cm from the deep margin.

My question, is this considered normal procedure.  Also, when a re-excision is done, do they generally remove a lot more tissue then when the lumpectomy is done?  Thank you