Cisco IPSec send errors

I have setup 3 different VPN tunnels from Cisco routers (3640 & 2901) to an ASA 5505 firewall.  Everything seems to work perfectly but on each router it shows exactly 3 send errors initially, then once the tunnels are up to the ASA, I do not get any errors.  What causes this, and is it a concern?

2901-B#sh crypto ipsec sa

interface: GigabitEthernet0/0
    Crypto map tag: CMAP, local addr 173.x.x.26

   protected vrf: (none)
   local  ident (addr/mask/prot/port): (172.28.100.0/255.255.255.0/0/0)
   remote ident (addr/mask/prot/port): (172.16.100.0/255.255.255.0/0/0)
   current_peer 173.x.x.17 port 500
     PERMIT, flags={origin_is_acl,}
    #pkts encaps: 105, #pkts encrypt: 105, #pkts digest: 105
    #pkts decaps: 110, #pkts decrypt: 110, #pkts verify: 110
    #pkts compressed: 0, #pkts decompressed: 0
    #pkts not compressed: 0, #pkts compr. failed: 0
    #pkts not decompressed: 0, #pkts decompress failed: 0
    #send errors 3, #recv errors 0

     local crypto endpt.: 173.x.x.26, remote crypto endpt.: 173.x.x.17
     path mtu 1500, ip mtu 1500, ip mtu idb GigabitEthernet0/0
     current outbound spi: 0xB85E1905(3093174533)
     PFS (Y/N): N, DH group: none

     inbound esp sas:
      spi: 0xF8C34C51(4173548625)
        transform: esp-256-aes esp-sha-hmac ,
        in use settings ={Tunnel, }
        conn id: 2001, flow_id: Onboard VPN:1, sibling_flags 80000046, crypto map: CMAP
        sa timing: remaining key lifetime (k/sec): (4557295/3548)
        IV size: 16 bytes
        replay detection support: Y
        Status: ACTIVE

     inbound ah sas:

     inbound pcp sas:

     outbound esp sas:
      spi: 0xB85E1905(3093174533)
        transform: esp-256-aes esp-sha-hmac ,
        in use settings ={Tunnel, }
        conn id: 2002, flow_id: Onboard VPN:2, sibling_flags 80000046, crypto map: CMAP
        sa timing: remaining key lifetime (k/sec): (4557304/3548)
        IV size: 16 bytes
        replay detection support: Y
        Status: ACTIVE

     outbound ah sas:

     outbound pcp sas: