[ubuntu-uk] Should I be worried by these strange 'trace routes'?

[mac]

Hi folks

Apologies if this is a off topic, but I could do with a bit of advice, 
and can't think where else to ask.

I have a Draytek router with 'DoS Defences' set up in the firewall, 
including 'block trace_route'.

A few weeks ago, I got email alerts from my router to say it was 
blocking trace routes coming from within a block of IP addresses owned 
by Internap Network Services in Georgia, USA. This happened a few days 
in a row. So I turned off my modem and router over night, and got 
reassigned a different dynamic IP by my ISP.

Today, my router alerted me that it was blocking the same source again 
trace routing my new IP address:

2015/03/27 19:45:23 --[DOS][Block][trace_route][70.42.24.18:36107-> 
<MyIPAddress>:33444][UDP][HLen=20,TLen=44]
2015/03/27 19:45:24 --[DOS][Block][trace_route][70.42.24.18:36107-> 
<MyIPAddress>:33445][UDP][HLen=20,TLen=44]
2015/03/27 19:45:28 --[DOS][Block][trace_route][70.42.24.24:36110-> 
<MyIPAddress>:33441][UDP][HLen=20,TLen=44]
2015/03/27 19:45:29 --[DOS][Block][trace_route][70.42.24.24:36110-> 
<MyIPAddress>:33442][UDP][HLen=20,TLen=44]
2015/03/27 19:45:33 --[DOS][Block][trace_route][70.42.24.27:36108-> 
<MyIPAddress>:33443][UDP][HLen=20,TLen=44]

I'm not running any servers on my home network, and I don't have any 
non-standard ports open.

I'm not very knowledgeable about networking. Tech support at my ISP was 
at a loss for an explanation of what's going on here.

I'd be really grateful for advice about whether and how I need to pursue 
this issue; and - if this is too off-topic here - where would be a good 
place to check this out further.

Many thanks in advance for any advice/suggestions.

mac