Premature poly-A site in exon

I’ve been looking at poly-A sites that overlap with CDS and I’ve
noticed a class of poly-A sites where there is no obvious STOP
codon to terminate the translation before the poly-A site:
the poly-A site occurs inside the curated CDS exon.

Most of these could conceivably be artefacts caused by the protocol
for isolating and PCRing up ESTs extending a small genomic run of A’s
to look like a poly-A tail, but one or two of them look compelling:

Gene Feature

F31D4.9 - WBsf026329
W05H7.4b/c/e - WBsf018718
M03A8.1 - WBsf027044 - a spurious one?
F02C12.1 - WBsf026947 - a spurious one?
T05A10.1a/b/c/d/e/f/g/h/i/j/k - WBsf027364
T07H8.4a/b/c/d/e/f/g - WBsf026757
- WBsf020025
- WBsf026763
- and other poly-A sites in this gene

The ones marked in red have poly-A sites defined by mRNA sequences instead of ESTs