mothur

Contigs larger than expected

Hoping someone can provide some insight. We sequence samples for the Ocular Microbiome. The samples are extremely low biomass so we use a linear amplification before targeting the V4 region. In the most recent batch, most of the contigs are much larger than we normally see. Usually everything is around 290 bp but this time we are seeing the result below. What could have happened? Do I need to trash these reads? Any help or ideas would be appreciated.

  Start End NBases Ambigs Polymer NumSeqs
Minimum: 1 35 35 0 2 1
2.5%-tile: 1 58 58 0 4 15624
25%-tile: 1 292 292 0 5 156235
Median:  1 380 380 1 6 312470
75%-tile: 1 475 475 3 11 468705
97.5%-tile: 1 498 498 35 35 609316
Maximum: 1 502 502 87 250 624939
Mean: 1 374.567 374.567 4.7231 9.01265
# of Seqs: 624939

I usually toss any seq with N, so most of the big ones would be tossed in my processing.